1. Field of the Disclosure
The present disclosure relates to a coating apparatus for a liquid crystal display (LCD) device, and particularly, to a coating apparatus having a coater chuck capable of improving a photoresist coating uniformity by preventing the sink of the coater chuck for performing a photoresist coating process in a manner of using a different type of material for making the coater chuck
2. Background of the Disclosure
A photolithography process for fabricating a semiconductor device or an LCD panel includes a coating process for coating a photoresist on a substrate, for example, a wafer, a glass and a mask, an exposure process of shifting the coated substrate into a device and printing a mask circuit in a circular shape onto the coated substrate, and a development process.
A photolithography process for fabricating a semiconductor device or an LCD panel includes a coating process for coating a photoresist on a substrate, for example, a wafer, a glass and a mask, an exposure process of shifting the coated substrate into a device and printing a mask circuit in a circular shape onto the coated substrate, and a development process.
FIG. 1 is an overview schematically showing a coating apparatus used in a coating process according to the related art.
FIG. 2 is an enlarged overview of a coater chuck present in the coating apparatus used in the coating process according to the related art.
FIG. 3 is an overview showing distances spaced between the coater chuck and a slit nozzle provided in the coating apparatus according to the related art.
FIG. 4 is a table showing spaced distances between the slit nozzle and the coater chuck, the probability of occurring the difference among the spaced distances and amounts of photoresist coated, upon employing the coater chuck present in the coating apparatus according to the related art.
As shown in FIGS. 1 and 2, the coating apparatus according to the related art may include a coater chuck 13 made of aluminum (Al). The coater chuck is connected to a servo motor 17 via a driving shaft 15 which is upwardly movable. Here, a surface-treated layer 13a for preventing the generation of static electricity is formed on the coater chuck 13. Since the aluminum is electrified with the slit nozzle to generate static electricity, sparkling may occur upon dispersing a photoresist through the slit nozzle. Thus, the surface-treated layer 13a is formed to prevent the occurrence of the sparkling.
Also, a chuck holder 19 for holding the coater chuck 13 is disposed at an upper end of the driving shaft 15.
A glass substrate 11 coated with the photoresist is placed on the coater chuck 13, and a slit nozzle 21 for dispersing the photoresist is located above one side of the glass substrate 11 with a preset distance. Here, the slit nozzle 21 disperses a photoresist 23 onto the glass substrate 11 for coating while moving from one end to another end of the glass substrate 11.
With the configuration of the coating apparatus according to the related art, the servo motor 17 drives the driving shaft 15. The coater chuck 13 is moved upwardly in response to the driving of the driving shaft 15, and the glass substrate 11 is then placed on the coater chuck 13. The slit nozzle 11 disposed above the one side of the glass substrate 11 with the preset distance then moves from one end to another of the glass substrate 11, thereby dispersing the photoresist 23 on the surface of the glass substrate 11 for coating.
However, the use of the coater chuck disposed in the coating apparatus employed for the photoresist coating process according to the related art has several problems.
The coater chuck for the coating apparatus employed for the photoresist coating process according to the related art is made of aluminum. Also, the glass substrate used in an LCD device fabrication process is large. Accordingly, in order to support the large glass substrate, a large coater chuck is needed. However, the thickness T1 of the aluminum making the large coater chuck, as shown in FIG. 2, is as thin as about 15 mm as compared to the size thereof. As a result, the side portions of the coater chuck 13, as shown in FIG. 3, are sunk downwardly.
As the side portions of the coater chuck 13 are sunk downwardly, as shown in FIG. 4, the difference among spaced distances G1, G2 and G2 between the slit nozzle 21 and the coater chuck 13 is caused, which results in an uneven distribution of the photoresist dispersed through the slit nozzle on the entire surface of the glass substrate 11. That is, the downward sinking of the side portions of the coater chuck 13 also causes the difference among the distance G2 between a central portion of the coater chuck 13 and the slit nozzle 21 and the distances G1 and G3 between both side portions of the coater chuck 13 and the silt nozzle 21. In particular, referring to FIG. 4, if the coater chuck 13 is formed of aluminum, the probability that the spaced distances between the slit nozzle 21 and the side portions of the coater chuck 13 are farther than the spaced distance between the slit nozzle 21 and the central portion of the coater chuck 13 is shown higher by about 50.3%.
Accordingly, the amounts of the photoresist dispersed onto the central portion and the side portions of the coater chuck become different, thereby causing an uneven coating of the photoresist. So, more photoresist is needed to be dispersed for a satisfactory photoresist coating, and responsively the speed that the slit nozzle moves becomes slower. Here, if the slit nozzle is kept moving fast, the photoresist coating uniformity on the entire glass substrate is deteriorated, so the moving speed of the slit nozzle is made slow enough to achieve a satisfactory photoresist coating result.
As such, due to the downward sinking of the side portions of the coater chuck made of aluminum, the photoresist is not difficult to be evenly dispersed on each position of the glass substrate and additionally a larger amount of photoresist is required, which makes the moving speed of the slit nozzle slow, resulting in increase in the time taken for performing the entire photoresist coating process.
Hence, the related art coating apparatus using the coater chuck made of the aluminum is difficult to evenly disperse the photoresist on each position of the glass substrate due to the downward sinking of the side portions of the aluminum coater chuck, and accordingly requires more photoresist. As a result, the speed that the slit nozzle moves becomes slower, thereby delaying the entire time of the photoresist coating process, resulting in increase in a material cost annually consumed.